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netfilter: xt_RATEEST: acquire xt_rateest_mutex for hash insert

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rateest_hash is supposed to be protected by xt_rateest_mutex,
and, as suggested by Eric, lookup and insert should be atomic,
so we should acquire the xt_rateest_mutex once for both.

So introduce a non-locking helper for internal use and keep the
locking one for external.

Reported-by: <syzbot+5cb189720978275e4c75@syzkaller.appspotmail.com>
Fixes: 5859034d7e ("[NETFILTER]: x_tables: add RATEEST target")
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Cong Wang 2018-02-05 14:41:45 -08:00 committed by Pablo Neira Ayuso
parent 992cfc7c5d
commit 7dc68e9875
1 changed files with 17 additions and 5 deletions
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22
net/netfilter/xt_RATEEST.c
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@ -39,23 +39,31 @@ static void xt_rateest_hash_insert(struct xt_rateest *est)
hlist_add_head(&est->list, &rateest_hash[h]);
}
struct xt_rateest *xt_rateest_lookup(const char *name)
static struct xt_rateest *__xt_rateest_lookup(const char *name)
{
struct xt_rateest *est;
unsigned int h;
h = xt_rateest_hash(name);
mutex_lock(&xt_rateest_mutex);
hlist_for_each_entry(est, &rateest_hash[h], list) {
if (strcmp(est->name, name) == 0) {
est->refcnt++;
mutex_unlock(&xt_rateest_mutex);
return est;
}
}
mutex_unlock(&xt_rateest_mutex);
return NULL;
}
struct xt_rateest *xt_rateest_lookup(const char *name)
{
struct xt_rateest *est;
mutex_lock(&xt_rateest_mutex);
est = __xt_rateest_lookup(name);
mutex_unlock(&xt_rateest_mutex);
return est;
}
EXPORT_SYMBOL_GPL(xt_rateest_lookup);
void xt_rateest_put(struct xt_rateest *est)
@ -100,8 +108,10 @@ static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
est = xt_rateest_lookup(info->name);
mutex_lock(&xt_rateest_mutex);
est = __xt_rateest_lookup(info->name);
if (est) {
mutex_unlock(&xt_rateest_mutex);
/*
* If estimator parameters are specified, they must match the
* existing estimator.
@ -139,11 +149,13 @@ static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
info->est = est;
xt_rateest_hash_insert(est);
mutex_unlock(&xt_rateest_mutex);
return 0;
err2:
kfree(est);
err1:
mutex_unlock(&xt_rateest_mutex);
return ret;
}